This project is concerned with the study of intestinal development as a model of cellular proliferation and differentiation. In the crypt and other model cell systems, de novo pyrimidine biosynthesis is being studied in relation to proliferative growth. In the intestinal villus, the brush border membrane-associated disaccharidases and absorptive transport functions are being used as markers of differentiation with genetic and environmental factors being examined in particular. Study of intestinal developmental disorders is included as a part of this research project. BIBLIOGRAPHIC REFERENCES: Sunshine, P., Sinatra, F.R. and Mitchell, C.H. Intractable Diarrhoae of Infancy. Clinics in Gastroenterology 6:445 (1977). Burrill, P. and Tsuboi, K.K. Characteristics of Cyclic-GMP Binding to the Isolated Rat Intestinal Brush Border Membrane. J. Supramolec. Struc. 6, 139 (1977).